Technical Field
This disclosure relates to a method for determining if maintenance is required on a contact of a connection jig. The connection jig uses multiple contacts to electronically connect a target object to be tested to a testing apparatus configured to test an electrical characteristic. More specifically, the disclosure relates to methods for determining if maintenance is needed on a contact, by determining when a contact of a connection jig should be replaced; and prompting a user to replace the contact before occurrence of a contact connection failure. The disclosure also relates to a testing apparatus having such contact maintenance function.
Related Art
In a typical circuit board, wires serve as paths through which ICs (Integrated Circuits), semiconductor components, and other electronic components transmit and receive electric signals to and from one another. With recent miniaturization of electronic components, such wires are being formed more finely, have become more complicated and also have been formed with lower resistance. As wires on a circuit board are formed more finely, a test as to whether or not the wire is defective has been required to be conducted with high accuracy. The test as to whether or not a wire is defective involves testing a continuity state and an insulation state of the wire. The continuity state is determined from a calculated resistance value between two test points defined on a wire. The insulation state is determined from a calculated resistance value between a wire to be tested and a different wire from the wire to be tested.
Wires are subjected to the tests described above by bringing a tip end of a conductive contact into contact with a test point defined on each wire. The contact establishes an electrical connection between the test point on the wire and a testing apparatus. The continuity test and the insulation test are conducted on the wires on the basis of electric signals transmitted and received by the testing apparatus.
As described above, a contact is configured to establish electrical connection between a testing apparatus and a test point. The contact generally has an elongated rod shape. Examples thereof may include a contact formed into a conductive probe shape, and a contact having a spring that expands and contracts in the longitudinal direction. The contact is a constituent of a testing jig having a plurality of contacts. In such testing jig, each of the contacts has a leading end that comes into contact with a test point, and a trailing end that comes into contact with an electrode of the testing jig that is electrically connected to a testing apparatus. In an actual test, the test point and the electrode are pressed against the contact so as to ensure the stability of electrical contact.
In a testing jig, the number of contacts corresponds to the number of test points to be defined on wires on a circuit board. A testing jig may have several hundred to several thousand contacts, depending on the type. The contacts of the testing jig repeatedly make contact with and release from wires on a circuit board. The contacts are used for testing a large number of circuit boards, for example, not less than 50,000 circuit boards per day. In such a case, each contact may repeatedly make contact with and release from wires 50,000 times each day. Therefore, the contact is required to be durable and also has to be quickly replaceable if the contact is determined to be abnormal.
As described above, a contact repeatedly contacts with and releases from a test point. In a case where the test point is formed of a solder bump, a fragment of the solder bump may adhere to the contact when the contact comes into contact with the solder bump. The fragment of the solder bump affects the contact state of the contact with the test point, which may result in failure to accurately conduct the test. Moreover, the contact, which repeatedly contacts with and releases from the test point many times, may become bent at a tip end thereof. The bent contact has to be replaced with a new one. However, when testing to determine whether or not a wire is defective, when the wire is determined to be defective, then further tests are needed to determine whether or not the wire is actually defective or whether or not the contact is abnormal.
Therefore, an abnormal contact cannot be recognized until a defective wire is detected. Japanese Patent Application JP 7-161783 A for example, discloses a technique for overcoming such a drawback. According to the technique disclosed in JP 7-161783 A, a tip end of a contact is irradiated with a laser beam in order to determine whether or not the contact is abnormal.
However, such method of detecting an abnormal contact requires additional time and effort. That is, the method requires a laser emitting mechanism (laser emitting part, light receiving part) for emitting the laser beam, and includes a step of determining whether or not the contact is abnormal.